[deirdresm]

Definitely too big. I use the FitBark GPS 2: https://help.fitbark.com/en/articles/6999814-what-are-the-fi...

Which is 47 mm x 30 mm x 15 mm vs the Mictrack's 46mm x 41mm x 16mm - and that 11 extra mm would make it not work on a collar. Fitbark does have Bluetooth.